It is often necessary or desirable for electronic circuits to work at high frequencies. In this context “high” may mean hundreds or thousands of MHz. Circuits may require the inclusion of non-transistor components. Such components may also be referred to as passive components, in that the components do not have current flow across PN junctions or other transistor-like properties as part of their fundamental operation.
Such passive components typically include resistors, capacitors, inductors and transformers. These components may be formed into filter or other circuit configurations where it is desirable that the substrate upon which they are formed exhibits low loss even at very high frequencies.